Metal-ligand multiple bonds are an important functionality given their application in processes such as cross metathesis, ring-opening metathesis, ring-closing metathesis, and ring-opening metathesis polymerization reactions. Most early-transition metal alkylidenes are prepared through an α-hydrogen abstraction route by creating a sterically crowded high-valent metal center which subsequently liberates an alkane upon addition of a base or by applying thermolysis. A milder route to generate titanium alkylidenes has been discovered within our group and such a strategy has been denoted oxidatively induced α-hydrogen abstraction reaction. This new synthetic protocol avoids the use of external bases or heat to initiate the α-hydrogen abstraction and provides a substitutionally labile anion for further reaction chemistries at the metal center.

Alkylidene complexes bearing either a bidentate β-diketiminate ligands or a more robust PNP pincer type ligand have been synthesized which demonstrates the ubiquity of this methodology. Alkylation of the titanium alkylidene complex provides rare examples of isolable alkylidene-alkyl complexes and α-Hydrogen abstraction of the alkylidene-alkyl complex generates the first examples of transient titanium-alkylidyne species. Mechanistic, computational, and isotopic labeling studies lend support for the existence of the putative titanium-alkylidyne intermediate. The neopentylidene-neopentyl complex (PNP)Ti=CH^tBu(CH ₂^tBu) has proven to be particularly reactive and can promote a series of intermolecular C–X (X = H, O, or F) bond cleavage reactions at room temperature. In addition, the titanium-alkylidyne was shown to ring-open pyridine at room temperature in the absence of harsh reductants. Addition of Me₃SiCl to the ring-opened product facilitates complete denitrogenation of the former pyridine ring.

In order to temper the remarkable reactivity of the titanium-alkylidyne intermediate, AlMe₃ was added to create an alkylidyne analogue of the Tebbe reagent. Similar to Tebbe's reagent, addition of a Lewis base unleashes the reactive potential of the alkylidyne functionality and can enable a series of transformations which include the facile and clean ring-opening of pyridine.